Serine/threonine kinase which acts as an essential component of the MAP kinase signal transduction pathway. MAPK1/ERK2 and MAPK3/ERK1 are the 2 MAPKs which play an important role in the MAPK/ERK cascade. They participate also in a signaling cascade initiated by activated KIT and KITLG/SCF. Depending on the cellular context, the MAPK/ERK cascade mediates diverse biological functions such as cell growth, adhesion, survival and differentiation through the regulation of transcription, translation, cytoskeletal rearrangements. The MAPK/ERK cascade plays also a role in initiation and regulation of meiosis, mitosis, and postmitotic functions in differentiated cells by phosphorylating a number of transcription factors. About 160 substrates have already been discovered for ERKs. Many of these substrates are localized in the nucleus, and seem to participate in the regulation of transcription upon stimulation. However, other substrates are found in the cytosol as well as in other cellular organelles, and those are responsible for processes such as translation, mitosis and apoptosis. Moreover, the MAPK/ERK cascade is also involved in the regulation of the endosomal dynamics, including lysosome processing and endosome cycling through the perinuclear recycling compartment (PNRC); as well as in the fragmentation of the Golgi apparatus during mitosis. The substrates include transcription factors (such as ATF2, BCL6, ELK1, ERF, FOS, HSF4 or SPZ1), cytoskeletal elements (such as CANX, CTTN, GJA1, MAP2, MAPT, PXN, SORBS3 or STMN1), regulators of apoptosis (such as BAD, BTG2, CASP9, DAPK1, IER3, MCL1 or PPARG), regulators of translation (such as EIF4EBP1) and a variety of other signaling-related molecules (like ARHGEF2, FRS2 or GRB10). Protein kinases (such as RAF1, RPS6KA1/RSK1, RPS6KA3/RSK2, RPS6KA2/RSK3, RPS6KA6/RSK4, SYK, MKNK1/MNK1, MKNK2/MNK2, RPS6KA5/MSK1, RPS6KA4/MSK2, MAPKAPK3 or MAPKAPK5) and phosphatases (such as DUSP1, DUSP4, DUSP6 or DUSP16) are other substrates which enable the propagation the MAPK/ERK signal to additional cytosolic and nuclear targets, thereby extending the specificity of the cascade.

Relations

Menin binds the jun family transcription factor jund and inhibits its transcriptional activity. The menin-jund interaction blocks jun n-terminal kinase (jnk)-mediated jund phosphorylation and suppresses jund-induced transcription. We found a role for phosphorylation of the ser100 residue of jund;jund phosphorylation were prevented by inhibitors of calcium, calmodulin, or erk1/2 kinase.

In several estrogen response element-containing genes, the s118a mutation strongly reduced induction by e(2), and u0126 did not further reduce expression. Here, we show that serines 104 (s104) and 106 (s106) are also phosphorylated by mapk in vitro and upon stimulation of mapk activity in vivo.Phosphorylation at serines 104 and 106 by erk1/2 mapk is important for estrogen receptor-alpha activity

In several estrogen response element-containing genes, the s118a mutation strongly reduced induction by e(2), and u0126 did not further reduce expression. Here, we show that serines 104 (s104) and 106 (s106) are also phosphorylated by mapk in vitro and upon stimulation of mapk activity in vivo.Phosphorylation at serines 104 and 106 by erk1/2 mapk is important for estrogen receptor-alpha activity

In several estrogen response element-containing genes, the s118a mutation strongly reduced induction by e(2), and u0126 did not further reduce expression. Here, we show that serines 104 (s104) and 106 (s106) are also phosphorylated by mapk in vitro and upon stimulation of mapk activity in vivo.Phosphorylation at serines 104 and 106 by erk1/2 mapk is important for estrogen receptor-alpha activity

In several estrogen response element-containing genes, the s118a mutation strongly reduced induction by e(2), and u0126 did not further reduce expression. Here, we show that serines 104 (s104) and 106 (s106) are also phosphorylated by mapk in vitro and upon stimulation of mapk activity in vivo.Phosphorylation at serines 104 and 106 by erk1/2 mapk is important for estrogen receptor-alpha activity

In several estrogen response element-containing genes, the s118a mutation strongly reduced induction by e(2), and u0126 did not further reduce expression. Here, we show that serines 104 (s104) and 106 (s106) are also phosphorylated by mapk in vitro and upon stimulation of mapk activity in vivo.

The genomic activity of ppargamma is modulated, in addition to ligand binding, by phosphorylation of a serine residue by mapks, such as extracellular signal-regulated protein kinases-1/2 (erk-1/2), or by nucleocytoplasmic compartmentalization through the erk activators mapk kinases-1/2 (mek-1/2). These mapks phosphorylate (in humans) ser 84 in the ppargamma1 and ser 114 in ppargamma2 isoform

The genomic activity of ppargamma is modulated, in addition to ligand binding, by phosphorylation of a serine residue by mapks, such as extracellular signal-regulated protein kinases-1/2 (erk-1/2), or by nucleocytoplasmic compartmentalization through the erk activators mapk kinases-1/2 (mek-1/2). These mapks phosphorylate (in humans) ser 84 in the ppargamma1 and ser 114 in ppargamma2 isoform

In this report, we describe the identification of five MAP kinase sites (S-1137, S-1167, S-1178, S-1193, and S-1197) on hSos1.Replacing the MAP kinase phosphorylation sites with alanine residues results in an increase in the binding affinity of Grb2 to hSos1

We now demonstrate that amino acids 1-92 of hPPARalpha contain an activation function (AF)-1-like domain, which is further activated by insulin through a pathway involving the mitogen-activated protein kinases p42 and p44. Further analysis of the amino-terminal region of PPARalpha revealed that the insulin-induced trans-activation occurs through the phosphorylation of two mitogen-activated protein kinase sites at positions 12 and 21, both of which are conserved across evolution.

We now demonstrate that amino acids 1-92 of hPPARalpha contain an activation function (AF)-1-like domain, which is further activated by insulin through a pathway involving the mitogen-activated protein kinases p42 and p44. Further analysis of the amino-terminal region of PPARalpha revealed that the insulin-induced trans-activation occurs through the phosphorylation of two mitogen-activated protein kinase sites at positions 12 and 21, both of which are conserved across evolution.

We report here that the important proangiogenic stimulus hypoxia stimulates phosphorylation, ubiquitination, and proteasomal breakdown of tal1 in endothelial cells. A specific serine in the putative transactivation domain of the protein, ser122, is preferentially phosphorylated by mapk in vitro.

We concluded that serine 142 of the tr dbd is the likely site of phosphorylation by t(4)-activated mapk and that the docking site on tr for activated mapk includes residues 128-133 (kgffrr), a basic amino acid-enriched motif novel for mapk substrates. Tr mutations in the proposed mapk docking domain and at residue 142 modulated t(4)-conditioned shedding of co-repressor and recruitment of co-activator proteins by the receptor, and they altered transcriptional activity of tr in a thyroid hormone response element-luciferase reporter assay.

We concluded that serine 142 of the tr dbd is the likely site of phosphorylation by t(4)-activated mapk and that the docking site on tr for activated mapk includes residues 128-133 (kgffrr), a basic amino acid-enriched motif novel for mapk substrates. Tr mutations in the proposed mapk docking domain and at residue 142 modulated t(4)-conditioned shedding of co-repressor and recruitment of co-activator proteins by the receptor, and they altered transcriptional activity of tr in a thyroid hormone response element-luciferase reporter assay.

Phosphorylation of grb10 by mitogen-activated protein kinase: identification of ser150 and ser476 of human grb10zeta as major phosphorylation sitesreplacing ser(150) and ser(476) with alanines reduced the inhibitory effect of human grb10zeta on insulin-stimulated irs1 tyrosine phosphorylation

Phosphorylation of grb10 by mitogen-activated protein kinase: identification of ser150 and ser476 of human grb10zeta as major phosphorylation sitesreplacing ser(150) and ser(476) with alanines reduced the inhibitory effect of human grb10zeta on insulin-stimulated irs1 tyrosine phosphorylation

Wstf, a specific component of two chromatin remodeling complexes (swi/snf-type winac and iswi-type wich), was phosphorylated by the stimulation of mapk cascades in vitro and in vivo. Ser-158 residue in the wac (wstf/acf1/cbpq46) domain, located close to the n terminus of wstf, was identified as a major phosphorylation target

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Erk1/2 are major ser-5 kinases after h2o2 treatment. These results suggest that subsequent to h2o2 treatment, the ser-5-phosphorylated form, but not the ser-2-phosphorylated form or the unphosphorylated form, is targeted for rapid proteasomal degradation through its ubiquitination.

Consensus phosphorylation sites for p42/44 MAPK and GSK-3 are present in the SP repeat of MCIP1 at serine 112 and serine 108, respectively |Several endogenous proteins are capable of inhibiting the catalytic activity of calcineurin. Modulatory calcineurin interacting protein 1 (MCIP1) is unique among these proteins on the basis of its pattern of expression and its function in a negative feedback loop to regulate calcineurin activity. Here we show that MCIP1 can be phosphorylated by MAPK and glycogen synthase kinase-3 and that phosphorylated MCIP1 is a substrate for calcineurin.

We show that jnk, erk, and p38 physically associate with the nfatc n-terminal regulatory domain and can directly phosphorylate functionally important residues involved in regulating nfatc subcellular localization, namely ser(172) and the conserved nfatc ser-pro repeats.

Mage-11 ser-174 appears to be a post-translational regulatory site phosphorylated by erk1, based on the inhibitory effect of the s174a mutation in the context of shorter ar nh2-terminal fragments (19), and the greater transcriptional activity of gal-mage-11 fusion proteins containing the s174d phosphomimetic.

Thus, fe65 has at least two apparently disparate functions and may also be involved in the pathogenesis of alzheimer's disease. The mechanisms by which fe65 trafficking and metabolism are regulated to fulfil these different roles are unclear. Our findings reported here, which demonstrate that fe65 is a phosphoprotein that is targeted by erk1/2 and which identify four in vivo phosphorylation sites, provide one possible mechanism whereby functional diversity might be achieved.

Thus, fe65 has at least two apparently disparate functions and may also be involved in the pathogenesis of alzheimer's disease. The mechanisms by which fe65 trafficking and metabolism are regulated to fulfil these different roles are unclear. Our findings reported here, which demonstrate that fe65 is a phosphoprotein that is targeted by erk1/2 and which identify four in vivo phosphorylation sites, provide one possible mechanism whereby functional diversity might be achieved.

Thus, fe65 has at least two apparently disparate functions and may also be involved in the pathogenesis of alzheimer's disease. The mechanisms by which fe65 trafficking and metabolism are regulated to fulfil these different roles are unclear. Our findings reported here, which demonstrate that fe65 is a phosphoprotein that is targeted by erk1/2 and which identify four in vivo phosphorylation sites, provide one possible mechanism whereby functional diversity might be achieved.

Thus, fe65 has at least two apparently disparate functions and may also be involved in the pathogenesis of alzheimer's disease. The mechanisms by which fe65 trafficking and metabolism are regulated to fulfil these different roles are unclear. Our findings reported here, which demonstrate that fe65 is a phosphoprotein that is targeted by erk1/2 and which identify four in vivo phosphorylation sites, provide one possible mechanism whereby functional diversity might be achieved.

More interestingly, ERK-dependent phosphorylation of MITF at Ser 73 is essential for MITF ubiquitinilation and degradation (87). Putting together all these findings, it can be proposed that MAPK activation inhibits melanogenesis due to an increased MITF degradation which is dependent on the MAPK-induced MITF phosphorylation and ubiquitinilation. In summary, although the phosphorylation of MITF at Ser73 increases its intrinsic transcriptional activity, this phosphorylation also targets MITF to the proteasome for its degradation. Consequently, the decrease in MITF levels leads to a down-regulation of melanogenic enzymes expression and to an inhibition of melanogenesis.

Lysrs serves as a key signaling molecule in the immune response by regulating gene expression. Lysrs was phosphorylated on serine 207 in a mapk-dependent manner, released from the multisynthetase complex, and translocated into the nucleus.

Ccaat/enhancer-binding protein alpha (c/ebpalpha) is one of the key transcription factors that mediate lineage specification and differentiation of multipotent myeloid progenitors into mature granulocytes.Here we report that inducers of monocyte differentiation inhibit the alternate cell fate choice, that of granulopoiesis, through inhibition of c/ebpalpha. This inhibition is mediated by extracellular signal-regulated kinases 1 and/or 2 (erk1/2), which interact with c/ebpalpha through an fxfp docking site and phosphorylate serine 21.

Tel became phosphorylated by erk on two serine residues, ser213 and ser257, in the internal domain between the hlh and ets domains. Tel lost its abilities to repress transcription through the phosphorylation.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

The pp90rsk phosphothreonine content paralleled the ERK1 activity more closely than the phosphoserine level. These results provide compelling evidence that in fibroblasts and PC12 cells ERK1 plays a direct role in the phosphorylation of pp90rsk and that pp90rsk represents a physiologically relevant substrate of extracellular-regulated kinases

Erk directly phosphorylated at least 13 proteins in vitro. Of these, nup50 was verified as a bona fide erk substrate. Notably, erk phosphorylation of the fg repeat region of nup50 reduced its affinity for importin-beta family proteins, importin-beta and transportin.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

Several lines of evidence indicate that the mapkap-k1 isoforms are also activated by mapks in vivo via the ras-dependent protein kinase cascade that is triggered by growth factors or tumor-promoting phorbol esters, such as phorbol 12-myristate 13-acetate (pma). here we identify six sites in mapkap-k1a that become phosphorylated in transfected cos-1 cells. The inactive form of mapkap-k1a in unstimulated cells is partially phosphorylated at ser222 and ser733. Stimulation with phorbol 12-myristate 13-acetate induces the phosphorylation of thr360, ser364, thr574, and ser381 and increases the phosphorylation of ser222 and ser733.

The pp90rsk phosphothreonine content paralleled the ERK1 activity more closely than the phosphoserine level. These results provide compelling evidence that in fibroblasts and PC12 cells ERK1 plays a direct role in the phosphorylation of pp90rsk and that pp90rsk represents a physiologically relevant substrate of extracellular-regulated kinases

Furthermore, we show that this gnrh-stimulated phosphorylation of the unliganded gr is mediated by a combination of the mapks jnk, p38, and erk as well as pkc in l t2 cells, because individual kinase inhibitors or combinations thereof inhibit this phosphorylation in intact cells.

Furthermore, we show that this gnrh-stimulated phosphorylation of the unliganded gr is mediated by a combination of the mapks jnk, p38, and erk as well as pkc in l t2 cells, because individual kinase inhibitors or combinations thereof inhibit this phosphorylation in intact cells.

Furthermore, we show that this gnrh-stimulated phosphorylation of the unliganded gr is mediated by a combination of the mapks jnk, p38, and erk as well as pkc in l t2 cells, because individual kinase inhibitors or combinations thereof inhibit this phosphorylation in intact cells.

We have generated two monoclonal antibodies that recognize two phosphorylated sites, p-ser227 and p-thr577, in the n- and c-terminal kinase domains of rsk2, respectively. phosphorylation and activation of rsk2 by uv light involves the erk pathway

We have generated two monoclonal antibodies that recognize two phosphorylated sites, p-ser227 and p-thr577, in the n- and c-terminal kinase domains of rsk2, respectively. phosphorylation and activation of rsk2 by uv light involves the erk pathway

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

Stress-induced stathmin phosphorylation is not de- pendent on ERK. Stathmin is also known to be phos- phorylated by ERK on Ser-25 and Ser-38 (17). Thus, it is possible that ERK phosphorylates stathmin in 293 cells|In subsequent reports (28, 29) it was shown that phosphorylation of stathmin blocks its ability to destabilize MTs.

Stress-induced stathmin phosphorylation is not de- pendent on ERK. Stathmin is also known to be phos- phorylated by ERK on Ser-25 and Ser-38 (17). Thus, it is possible that ERK phosphorylates stathmin in 293 cells|In subsequent reports (28, 29) it was shown that phosphorylation of stathmin blocks its ability to destabilize MTs.

These studies confirm that connexin-43 is a MAP kinase substrate in vivo and that phosphorylation on Ser255, Ser279, and/or Ser282 initiates the down-regulation of gap junctional communication. Studies with connexin-43 mutants suggest that MAP kinase phosphorylation at one or more of the tandem Ser279/Ser282 sites is sufficient to disrupt gap junctional intercellular communication.

These studies confirm that connexin-43 is a MAP kinase substrate in vivo and that phosphorylation on Ser255, Ser279, and/or Ser282 initiates the down-regulation of gap junctional communication. Studies with connexin-43 mutants suggest that MAP kinase phosphorylation at one or more of the tandem Ser279/Ser282 sites is sufficient to disrupt gap junctional intercellular communication.

These studies confirm that connexin-43 is a MAP kinase substrate in vivo and that phosphorylation on Ser255, Ser279, and/or Ser282 initiates the down-regulation of gap junctional communication. Studies with connexin-43 mutants suggest that MAP kinase phosphorylation at one or more of the tandem Ser279/Ser282 sites is sufficient to disrupt gap junctional intercellular communication.

Hsp22 is phosphorylated by protein kinase c (at residues ser(14) and thr(63)) and by p44 mitogen-activated protein kinase (at residues ser(27) and thr(87)). Concerning the possible function of hsp22, no definitive conclusions can be drawn with the available data, although its function might be to bind to and modulate the activity of hsp27.Some Studies claimed that phosphorylation is required for the translocation

Hsp22 is phosphorylated by protein kinase c (at residues ser(14) and thr(63)) and by p44 mitogen-activated protein kinase (at residues ser(27) and thr(87)). Concerning the possible function of hsp22, no definitive conclusions can be drawn with the available data, although its function might be to bind to and modulate the activity of hsp27.Some Studies claimed that phosphorylation is required for the translocation

Hsp22 is phosphorylated by protein kinase c (at residues ser(14) and thr(63)) and by p44 mitogen-activated protein kinase (at residues ser(27) and thr(87)). Concerning the possible function of hsp22, no definitive conclusions can be drawn with the available data, although its function might be to bind to and modulate the activity of hsp27.Some Studies claimed that phosphorylation is required for the translocation

Hsp22 is phosphorylated by protein kinase c (at residues ser(14) and thr(63)) and by p44 mitogen-activated protein kinase (at residues ser(27) and thr(87)). Concerning the possible function of hsp22, no definitive conclusions can be drawn with the available data, although its function might be to bind to and modulate the activity of hsp27.Some Studies claimed that phosphorylation is required for the translocation

We found that in these cells, lipopolysaccharide stimulates the expression of mhc ii genes via the activation of erk1/2, which is mediated by toll-like receptor 4. Erk1/2 then phosphorylates the serine at position 357, which is located in a degron of ciita isoform 1 that leads to its monoubiquitylation.

Accumulating evidence indicates that protein phosphorylation regulates nox activity. In this report, we show that serine282 residue of nox activator 1 (noxa1) is phosphorylated by erk in response to egf resulting in desensitization of nox1 activity

In this study we show that the extracellular signal-regulated kinases 1 and 2 (erk1/2) interact directly with ciita, targeting serine residues in the amino terminus of the protein, including serine 288. These data suggest a model whereby erk1/2-mediated phosphorylation of ciita down-regulates ciita activity by priming it for nuclear export, thus providing a means for cells to tightly regulate the extent of antigen presentation.

Erk-induced raf-1 phosphorylation sustains raf-1 kinase activity furthermore, using direct in vitro phosphorylation we show that these sites are direct targets of erk-1 and using phosphospecific antibodies developed against one of the sites, s296, show that these sites are physiological phosphorylation sites induced in vivo after mitogen stimulation.

Phosphorylation of histone h3 at serine 10 is indispensable for neoplastic cell transformation. When h3 wt was overexpressed, egf induction of c-fos and c-jun promoter activity was significantly increased compared with control cells but not in the h3 mutant s10a or s28a cells.

We previously established that phosphorylation of lsf in early g1 at ser-291 and ser-309 inhibits its transcriptional activity and that dephosphorylation later in g1 is required for its reactivation. At the peak activities of erk and cyclin c/cdk2 in early g1, lsf is efficiently phosphorylated on ser-291 and ser-309.

We previously established that phosphorylation of lsf in early g1 at ser-291 and ser-309 inhibits its transcriptional activity and that dephosphorylation later in g1 is required for its reactivation. At the peak activities of erk and cyclin c/cdk2 in early g1, lsf is efficiently phosphorylated on ser-291 and ser-309.

Thus, we propose that mapk phosphorylation of amphiphysin1 controls ngf receptor/trka-mediated endocytosis by terminating the amphiphysin1-ap-2 interaction.Our results indicate that phosphorylation of amphiphysin 1 at ser-285 and/or ser-293 affects the function of amphiphysin1.Mapk phosphorylation of ser-285 and ser-293 could modulate the interaction between prd and ap-2, resulting in the dissociation of amphiphysin1 from ap-2.

Thus, we propose that mapk phosphorylation of amphiphysin1 controls ngf receptor/trka-mediated endocytosis by terminating the amphiphysin1-ap-2 interaction.Our results indicate that phosphorylation of amphiphysin 1 at ser-285 and/or ser-293 affects the function of amphiphysin1.Mapk phosphorylation of ser-285 and ser-293 could modulate the interaction between prd and ap-2, resulting in the dissociation of amphiphysin1 from ap-2.

Specifically, down-regulation of mature prs occurs by a mechanism in which ligand binding activates pr phosphorylation by mapks at a unique serine residue, which then targets the receptors for degradation.

Using mass spectrometry, we identified raf-1 phosphorylation on three sp motif sites: s289/s296/s301. These sites were phosphorylated by extracellular signal-regulated kinase (erk)-1 in vitro, and their phosphorylation in vivo was dependent on endogenous erk activity. Functionally, erk-1 expression sustains raf-1 activation in a manner dependent on raf-1 phosphorylation on the identified sites, and s289/296/301a substitution markedly decreases the in vivo activity of raf-1 s259a.

Mapkerk1/2 is also able to phopshorylate the egf receptor, the ras exchange factor sos, mkkkraf1, and mkkmek1. The phosphorylation of each of these proteins by mapkerk1/2 is believed to reduce their catalytic activity. previous studies have shown that phosphorylation is required for raf-1 activation, and here, we identify six phosphorylation sites that contribute to the downregulation of raf-1 after mitogen stimulation. Five of the identified sites are proline-directed targets of activated erk

Mapkerk1/2 is also able to phopshorylate the egf receptor, the ras exchange factor sos, mkkkraf1, and mkkmek1. The phosphorylation of each of these proteins by mapkerk1/2 is believed to reduce their catalytic activity. previous studies have shown that phosphorylation is required for raf-1 activation, and here, we identify six phosphorylation sites that contribute to the downregulation of raf-1 after mitogen stimulation. Five of the identified sites are proline-directed targets of activated erk

Here we show that antigen receptor activation leads to bcl-6 phosphorylation by mitogen-activated protein kinase (mapk). Phosphorylation, in turn, targets bcl-6 for rapid degradation by the ubiquitin/proteasome pathway.

Here we show that antigen receptor activation leads to bcl-6 phosphorylation by mitogen-activated protein kinase (mapk). Phosphorylation, in turn, targets bcl-6 for rapid degradation by the ubiquitin/proteasome pathway.

Inhibitors of the erk1/2 pathway abrogated gm-csf-induced phosphorylation of ser345, while p38 mapk inhibitor abrogated tnf-alpha-induced phosphorylation of ser345.These results show that the ala-mutated p47phox acts as a dominant-negative inhibitor of endogenous p47phox and clearly indicate that phosphorylation of ser345 is required for the priming of nadph oxidase activity in neutrophil-like cells.

Mkp-1 was a target in vivo and in vitro for p42(mapk) or p44(mapk), which phosphorylates mkp-1 on two carboxyl-terminal serine residues, serine 359 and serine 364. This phosphorylation did not modify mkp-1's intrinsic ability to dephosphorylate p44(mapk) but led to stabilization of the protein.

Mkp-1 was a target in vivo and in vitro for p42(mapk) or p44(mapk), which phosphorylates mkp-1 on two carboxyl-terminal serine residues, serine 359 and serine 364. This phosphorylation did not modify mkp-1's intrinsic ability to dephosphorylate p44(mapk) but led to stabilization of the protein.

In the present study, we show that, in addition to being phosphorylated on thr-581 and ser-360 by erk1/2 or p38, msk1 can autophosphorylate on at least six sites: ser-212, ser-376, ser-381, ser-750, ser-752 and ser-758.

In the present study, we show that, in addition to being phosphorylated on thr-581 and ser-360 by erk1/2 or p38, msk1 can autophosphorylate on at least six sites: ser-212, ser-376, ser-381, ser-750, ser-752 and ser-758.

In a previous study we have observed that exposure of nih 3t3 cells to pdgf or serum leads to c-fos phosphorylation by erk on specific residues, thr232, thr325, thr331, and ser374, within the cooh-terminal c-fos tad we have recently shown that erk phosphorylates multiple residues within the carboxylterminal transactivation domain (tad) of c-fos, thus resulting in its increased transcriptional activity.

Phosphorylation of the c-fos and c-jun hob1 motif stimulates its activation capacity here we show that the hob1-containing activation domain of c-fos is stimulated by ha-ras in vivo and phosphorylated by a map kinase family member in vitro and that mutating t232 to ala abolishes both functions.

In a previous study we have observed that exposure of nih 3t3 cells to pdgf or serum leads to c-fos phosphorylation by erk on specific residues, thr232, thr325, thr331, and ser374, within the cooh-terminal c-fos tad we have recently shown that erk phosphorylates multiple residues within the carboxylterminal transactivation domain (tad) of c-fos, thus resulting in its increased transcriptional activity.

In a previous study we have observed that exposure of nih 3t3 cells to pdgf or serum leads to c-fos phosphorylation by erk on specific residues, thr232, thr325, thr331, and ser374, within the cooh-terminal c-fos tad we have recently shown that erk phosphorylates multiple residues within the carboxylterminal transactivation domain (tad) of c-fos, thus resulting in its increased transcriptional activity.

In the present study, we show that, in addition to being phosphorylated on Thr-581 and Ser-360 by ERK1/2 or p38, MSK1 can autophosphorylate on at least six sites: Ser-212, Ser-376, Ser-381, Ser-750, Ser-752 and Ser-758. Of these sites, the N-terminal T-loop residue Ser-212 and the 'hydrophobic motif' Ser-376 are phosphorylated by the C-terminal kinase domain of MSK1, and their phosphorylation is essential for the catalytic activity of the N-terminal kinase domain of MSK1

We demonstrate that perk 1/2 can phosphorylate pro-caspase-8 at s387 by knocking-down the endogenous pro-caspase-8 using rnai and replacing it with its non-phosphorylatable counterpart (s387a), a significant increase in caspase-8 activity

Erk1 and erk2 phosphorylate beta-arrestin1 at ser-412 in vitro. . in the resting state, cytosolic arrestin1 proteins are constitutively phosphorylated by extracellular signal-regulated kinase (erk) at ser412, located within their distal c terminus. erk-phosphorylated arrestin1 is unable to associate with clathrin cages, whereas this constraint is removed upon its dephosphorylation

Erk1 and erk2 phosphorylate beta-arrestin1 at ser-412 in vitro. . in the resting state, cytosolic arrestin1 proteins are constitutively phosphorylated by extracellular signal-regulated kinase (erk) at ser412, located within their distal c terminus. erk-phosphorylated arrestin1 is unable to associate with clathrin cages, whereas this constraint is removed upon its dephosphorylation

Erk1 and erk2 phosphorylate beta-arrestin1 at ser-412 in vitro. . in the resting state, cytosolic arrestin1 proteins are constitutively phosphorylated by extracellular signal-regulated kinase (erk) at ser412, located within their distal c terminus. erk-phosphorylated arrestin1 is unable to associate with clathrin cages, whereas this constraint is removed upon its dephosphorylation

Phosphorylation of serine-59 on p56lck in vivo, which correlated with the shift to p60lck. We also demonstrated that the same serine residue could be phosphorylated in vitro with mitogen-activated protein kinases and that this event was capable of reducing p56lck activity in vitro.

Negative regulation of the LKB1/AMPK pathway by ERK in human acute myeloid leukemia cellsBRAFV600E activates downstream molecules, including ERK and p90 ribosomal S6 kinase (RSK), and leads to the phosphorylation of LKB-1 at Ser428 by these kinases. This cascade results in the dissociation of LKB1 from AMPK.

Serum induces rhoa-dependent translocation of mkl1 from the cytoplasm to the nucleus and also causes a rapid increase in mkl1 phosphorylation. Serum-induced phosphorylation of the serum response factor coactivator mkl1 by the extracellular signal-regulated kinase 1/2 pathway inhibits its nuclear localization.

Serum induces rhoa-dependent translocation of mkl1 from the cytoplasm to the nucleus and also causes a rapid increase in mkl1 phosphorylation. Serum-induced phosphorylation of the serum response factor coactivator mkl1 by the extracellular signal-regulated kinase 1/2 pathway inhibits its nuclear localization.

Phosphorylation of kinesin light chain 1 at serine 460 modulates binding and trafficking of calsyntenin-1mutation of klc1ser460 to an alanine residue, to preclude phosphorylation, increased the binding of calsyntenin-1, whereas mutation to an aspartate residueklc1ser460 is a predicted mitogen-activated protein kinase (mapk) target site, and we show that extracellular-signal-regulated kinase (erk) phosphorylates this residue in vitro.

A rare, missense polymorphism, s470n, was identified in the synapsin iii gene and appeared more frequently in individuals with schizophrenia than in controls. Ser470, was determined to be a substrate for mitogen-activated protein kinase, a downstream effector of neurotrophin action.

Epidermal growth factor activates m-calpain (calpain ii), at least in part, by extracellular signal-regulated kinase-mediated phosphorylation.We now show that erk directly phosphorylates and activates m-calpain both in vitro and in vivo. We identified serine 50 as required for epidermal growth factor (egf)-induced calpain activation in vitro and in vivo.

These results indicate that phosphorylation of nup153 and nup214 by erk strongly reduces their affinity for importin-. nup153 depletion caused a strong inhibition of nuclear accumulation of gfp?importin-beta in both erk-inhibited and erk-activated cells (fig. 8b,c), indicating that nup153 is essential for the efficient importin-beta transport.

These results indicate that phosphorylation of nup153 and nup214 by erk strongly reduces their affinity for importin-. nup153 depletion caused a strong inhibition of nuclear accumulation of gfp?importin-beta in both erk-inhibited and erk-activated cells (fig. 8b,c), indicating that nup153 is essential for the efficient importin-beta transport.

Here we describe that human c-myb can be phosphorylated by mitogen-activated protein kinases (mapk's) at serine 532 of the carboxy (c-) terminal regulatory domain in vitro. expression of a constitutively active form of ras together with c-myb in transient transfection experiments had no effect on the transcriptional activity of c-myb, while expression of a polypeptide containing the c-myb c-terminal domain stimulated c-myb activity. This effect is reduced upon mapk-dependent phosphorylation of serine 532.

Functional analysis of phosphorylation at serine 532 of human c-myb by map kinase. expression of a polypeptide containing the c-myb c-terminal domain stimulated c-myb activity. This effect is reduced upon mapk-dependent phosphorylation of serine 532. Our data suggest that the mapk-dependent state of phosphorylation modifies the cellular function of c-myb by modulating its interaction with a putative inhibitory factor

Here, we show that Erk may play a critical role in TSC progression through posttranslational inactivation of TSC2. Erk-dependent phosphorylation leads to TSC1-TSC2 dissociation and markedly impairs TSC2 ability to inhibit mTOR signaling, cell proliferation, and oncogenic transformation. |Serine to alanine substitution at S664 or double S664A/S540A mutagenesis resulted in a marked reduction in TSC2 phosphorylation to a similar extent. In contrast, S540A substitution only moderately impaired TSC2 phosphorylation (Figure 3D), corroborating the notion that in vivo S664 is the most relevant residue for Erk-mediated phosphorylation.

Here, we show that Erk may play a critical role in TSC progression through posttranslational inactivation of TSC2. Erk-dependent phosphorylation leads to TSC1-TSC2 dissociation and markedly impairs TSC2 ability to inhibit mTOR signaling, cell proliferation, and oncogenic transformation. |Serine to alanine substitution at S664 or double S664A/S540A mutagenesis resulted in a marked reduction in TSC2 phosphorylation to a similar extent. In contrast, S540A substitution only moderately impaired TSC2 phosphorylation (Figure 3D), corroborating the notion that in vivo S664 is the most relevant residue for Erk-mediated phosphorylation.

Phosphorylation at Ser-59 (or alternatively, its mutation to Glu) reverses the inhibition and allows interaction of the p56lck SH2 domain with p62.|phosphotyrosine-independent binding of p62 to the p56lck SH2 domain appears to provide an alternative pathway for p56lck signaling that is regulated by Ser-59 phosphorylation.

PKCalpha, which was activated in senescent cells by ROS strongly activated Erk1/2, and the SA-pErk1/2 in turn phosphorylated Sp1 on Ser(59). Sp1-enhanced transcription of p21(Sdi1) resulted in regulation of cellular senescence in primary human diploid fibroblast cells.

We showed that perifosine activates the mitogen-activated protein/extracellular signal-regulated kinase pathway, and this activation promotes the phosphorylation of sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased sp1 binding and enhanced p21(waf1/cip1) transcription.

We showed that perifosine activates the mitogen-activated protein/extracellular signal-regulated kinase pathway, and this activation promotes the phosphorylation of sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased sp1 binding and enhanced p21(waf1/cip1) transcription.

We showed that perifosine activates the mitogen-activated protein/extracellular signal-regulated kinase pathway, and this activation promotes the phosphorylation of sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased sp1 binding and enhanced p21(waf1/cip1) transcription.

We showed that perifosine activates the mitogen-activated protein/extracellular signal-regulated kinase pathway, and this activation promotes the phosphorylation of sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased sp1 binding and enhanced p21(waf1/cip1) transcription.

Here we show that p42/p44 mapk directly phosphorylates sp1 on threonines 453 and 739 both in vitro and in vivo. sa-perk1/2 activates the transcription factor, sp1, via ser59 phosphorylation downstream of pkc_, leading to transcription of p21sdi1 and resulting in replicative senescence of hdf cells.

Rin beta-cells exposed to high glucose exhibited increased c-jun n-terminal kinase (jnk) and erk1/2 activity, which was associated with increased irs-1 phosphorylation at serine (ser)(307) and ser(612), respectively, that inhibits coupling of irs-1 to the insulin receptor and is upstream of the inhibition of irs-1 tyrosine phosphorylation.

SCG10, a growth cone-enriched MT-destabilizing protein, has been recently characterized as an in vitro substrate for various serine/threonine kinases including PKA, MAP kinase, and CDK (19). We have found that SCG10 is phosphorylated in vivo in developing rat brain.| The sites for MAP kinase phosphorylation were identified as Ser-62 and Ser-73 of SCG10|By expressing a series of phosphorylation site mutants, we showed that the MT-destabilizing effect of SCG10 could be modulated. While the nonphosphorylatable mutant showed higher activity than the wild-type protein, the activity of the mutant in which phosphorylation on all four sites was mimicked by an aspartate residue was greatly reduced. These data suggest that the nonphosphorylated state of SCG10 represents the most active form of the protein.

SCG10, a growth cone-enriched MT-destabilizing protein, has been recently characterized as an in vitro substrate for various serine/threonine kinases including PKA, MAP kinase, and CDK (19). We have found that SCG10 is phosphorylated in vivo in developing rat brain.| The sites for MAP kinase phosphorylation were identified as Ser-62 and Ser-73 of SCG10|By expressing a series of phosphorylation site mutants, we showed that the MT-destabilizing effect of SCG10 could be modulated. While the nonphosphorylatable mutant showed higher activity than the wild-type protein, the activity of the mutant in which phosphorylation on all four sites was mimicked by an aspartate residue was greatly reduced. These data suggest that the nonphosphorylated state of SCG10 represents the most active form of the protein.

Phosphorylation of grb2-associated binder 2 on serine 623 by erk mapk regulates its association with the phosphatase shp-2 and decreases stat5 activation.We and others have demonstrated that il-2-induced tyrosine phosphorylation of gab2 and its interaction with its sh2 domain-containing partners, shp-2, p85 pi3k, and crkl (5, 26, 27). we report that pretreatment of kit 225 cells with the mek inhibitor u0126, strongly decreased the characteristic shift of gab2 in response to il-2 and increased gab2/shp-2 association, an effect that could be ascribed to erk phosphorylation of serine 623.

We show that at least two different nuclear protein kinases, one of them identified as p42/p44 mapk, can modify hif-1_. Analysis of in vitro phosphorylated hif-1_ by mass spectroscopy revealed residues ser-641 and ser-643 as possible mapk phosphorylation sites these data suggest that phosphorylation of ser-641/643 by mapk promotes the nuclear accumulation and transcriptional activity of hif-1_

We show that at least two different nuclear protein kinases, one of them identified as p42/p44 mapk, can modify hif-1_. Analysis of in vitro phosphorylated hif-1_ by mass spectroscopy revealed residues ser-641 and ser-643 as possible mapk phosphorylation sites these data suggest that phosphorylation of ser-641/643 by mapk promotes the nuclear accumulation and transcriptional activity of hif-1_

Tfii-i can be phosphorylated in vitro by erk and mutation of consensus map kinase substrate sites at serines 627 and 633 impairs the phosphorylation of tfii-i by erk and its activity on the c-fos promoter. These results suggest that erk regulates the activity of tfii-i by direct phosphorylation.

Tfii-i can be phosphorylated in vitro by erk and mutation of consensus map kinase substrate sites at serines 627 and 633 impairs the phosphorylation of tfii-i by erk and its activity on the c-fos promoter. These results suggest that erk regulates the activity of tfii-i by direct phosphorylation.

The formation of rsk-nfatc4-dna transcription complex is also apparent upon adipogenesis. Bound rsk phosphorylates ser(676) and potentiates nfatc4 dna binding by escalating nfat-dna association. Ser(676) is also targeted by the erk map kinase, which interacts with nfat at a distinct region than rsk. Thus, integration of the erk/rsk signaling pathway provides a mechanism to modulate nfatc4 transcription activity.

In vitro, bimel was phosphorylated by extracellular signal-regulated kinase on ser(69), which resides in the bimel-specific insert region. Using phosphospecific antibody against this site, we show that this residue is actually phosphorylated in cells. We also show that phosphorylation of ser(69) promotes ubiquitination of bimel. We conclude that mek inhibitors sensitize mda-mb231 and hbc4 cells to anoikis by blocking phosphorylation and hence degradation of bimel

We found three proline-directed residues within raptor, ser(8), ser(696), and ser(863), which are directly phosphorylated by erk1/2. Expression of phosphorylation-deficient alleles of raptor revealed that phosphorylation of these sites by erk1/2 normally promotes mtorc1 activity and signaling to downstream substrates, such as 4e-bp1.

We found three proline-directed residues within raptor, ser(8), ser(696), and ser(863), which are directly phosphorylated by erk1/2. Expression of phosphorylation-deficient alleles of raptor revealed that phosphorylation of these sites by erk1/2 normally promotes mtorc1 activity and signaling to downstream substrates, such as 4e-bp1.

Arsenite treatment of cells activates p38_ and induces interaction between p38_ and Raptor, a regulatory component of mTORC1, resulting in phosphorylation of Raptor on Ser(863) and Ser(771). The phosphorylation of Raptor on these sites enhances mTORC1 activity, and contributes largely to arsenite-induced mTORC1 activation

We found three proline-directed residues within raptor, ser(8), ser(696), and ser(863), which are directly phosphorylated by erk1/2. Expression of phosphorylation-deficient alleles of raptor revealed that phosphorylation of these sites by erk1/2 normally promotes mtorc1 activity and signaling to downstream substrates, such as 4e-bp1.

Erk1 and erk2 directly phosphorylate bcl2 exclusively at ser-70 p44mapk/extracellular signal-regulated kinase 1 (erk1) and p42 mapk/erk2 are activated by il-3, colocalize with mitochondrial bcl2, and can directly phosphorylate bcl2 on ser-70 in a stauro-resistant manner both in vitro and in vivo molecular association.

These straddle the target residue, ser(579), for erk2 phosphorylation of pde4d3. Mutation of either or both of these docking sites prevented erk2 from being co-immunoprecipitated with pde4d3, ablated the ability of epidermal growth factor to inhibit pde4d3 through erk2 action in transfected cos cells, and attenuated the ability of erk2 to phosphorylate pde4d3 in vitro.

The hematopoietic-specific Galpha16 protein has recently been shown to mediate receptor-induced activation of the signal transducer and activator of transcription 3 (STAT3). In the present study, we have delineated the mechanism by which Galpha16 stimulates STAT3 in human embryonic kidney 293 cells. A constitutively active Galpha16 mutant, Galpha16QL, stimulated STAT3-dependent luciferase activity as well as the phosphorylation of STAT3 at both Tyr705 and Ser727. Galpha16QL-induced STAT3 activation was enhanced by overexpression of extracellular signal-regulated kinase 1 (ERK1),

Extracellular signal-regulated kinases (erks) phosphorylate the high molecular mass isoform of the actin-binding protein caldesmon (h-cad) at two sites (ser(759) and ser(789)) during smooth muscle stimulation. Nmr spectroscopy shows that the actin binding properties of the minimal inhibitory region of caldesmon, residues 750-779, alter upon map kinase phosphorylation of ser-759, a residue not involved in actin binding. This phosphorylation leads to markedly diminished actin affinity as a result of the loss of interaction at one of the two sites that bind to f-actin.

Extracellular signal-regulated kinases (erks) phosphorylate the high molecular mass isoform of the actin-binding protein caldesmon (h-cad) at two sites (ser(759) and ser(789)) during smooth muscle stimulation. Nmr spectroscopy shows that the actin binding properties of the minimal inhibitory region of caldesmon, residues 750-779, alter upon map kinase phosphorylation of ser-759, a residue not involved in actin binding. This phosphorylation leads to markedly diminished actin affinity as a result of the loss of interaction at one of the two sites that bind to f-actin.

The precursor form of the cytokine il-16 (proil-16) was shown to be phosphorylated on ser144 in antigen receptor-, sdf1alpha- and il-2-activated t cells. Genetic and pharmacological-inhibitor experiments showed that the phosphorylation of proil-16 is dependent on activation of the kinases erk1/2. Il-16 is secreted by mitogen-activated t cells, and the biochemical link between proil-16 and erk1/2, revealed by studies with pap-1, prompted analysis of the role of map kinases in this response.

Lat, an adapter protein essential for t-cell signaling, is phosphorylated at its thr 155 by erk in response to t-cell receptor stimulation. Thr 155 phosphorylation reduces the ability of lat to recruit plcgamma1 and slp76, leading to attenuation of subsequent downstream events such as [ca2+]i mobilization and activation of the erk pathway.

Dephosphorylation and Inactivation of ERKs|ERK1 phosphorylated on either threonine (ERK1*Y204F) or tyrosine alone (ERK1*T202A) was utilized as a substrate for HVH2. Threonine 202 and tyrosine 204 in ERK1 (53) correspond to threonine 183 and tyrosine 185 in ERK2 which are the activation-phosphorylation sites by MEK(14, 15, 16). ERK1*, a kinase-deficient mutant, was phosphorylated on both threonine and tyrosine by MEK2 (Fig. 3B). ERK1*T202A, having threonine 202 substituted by an alanine, was phosphorylated only on tyrosine while ERK1*Y204F, having tyrosine 204 substituted by a phenylalanine, was phosphorylated only on threonine (Fig. 3B). GST-HVH2 dephosphorylated all three ERK1* mutants (Fig. 3A), suggesting that double phosphorylations of adjacent threonine and tyrosine were not a prerequisite for HVH2 recognition. However, HVH2 dephosphorylated ERK1* and ERK1*T202A more efficiently than ERK1*Y204F (Fig. 3A), indicating that HVH2 preferred phosphotyrosine over phosphothreonine. Interestingly, MEK also phosphorylated tyrosine residues more efficiently than threonine residues of ERK

Dephosphorylation and Inactivation of ERKs|ERK1 phosphorylated on either threonine (ERK1*Y204F) or tyrosine alone (ERK1*T202A) was utilized as a substrate for HVH2. Threonine 202 and tyrosine 204 in ERK1 (53) correspond to threonine 183 and tyrosine 185 in ERK2 which are the activation-phosphorylation sites by MEK(14, 15, 16). ERK1*, a kinase-deficient mutant, was phosphorylated on both threonine and tyrosine by MEK2 (Fig. 3B). ERK1*T202A, having threonine 202 substituted by an alanine, was phosphorylated only on tyrosine while ERK1*Y204F, having tyrosine 204 substituted by a phenylalanine, was phosphorylated only on threonine (Fig. 3B). GST-HVH2 dephosphorylated all three ERK1* mutants (Fig. 3A), suggesting that double phosphorylations of adjacent threonine and tyrosine were not a prerequisite for HVH2 recognition. However, HVH2 dephosphorylated ERK1* and ERK1*T202A more efficiently than ERK1*Y204F (Fig. 3A), indicating that HVH2 preferred phosphotyrosine over phosphothreonine. Interestingly, MEK also phosphorylated tyrosine residues more efficiently than threonine residues of ERK

We demonstrate that ERK, JNK, and p38 are activated by distinct combinations of stimuli in T cells that simulate full or partial activation through the T cell receptor. These kinases are regulated by reversible phosphorylation on Tyr and Thr, and the dual specific phosphatases PAC1 and MKP-1 previously have been implicated in the in vivo inactivation of ERK or of ERK and JNK, respectively

We demonstrate that ERK, JNK, and p38 are activated by distinct combinations of stimuli in T cells that simulate full or partial activation through the T cell receptor. These kinases are regulated by reversible phosphorylation on Tyr and Thr, and the dual specific phosphatases PAC1 and MKP-1 previously have been implicated in the in vivo inactivation of ERK or of ERK and JNK, respectively

Phosphorylation decreased the ability of mbp to polymerize actin and to bundle actin filaments but had no effect on the dissociation constant of the mbp-actin complex or on the ability of ca2+-calmodulin to dissociate the complex. The most significant effect of phosphorylation on the mbp-actin complex was a dramatic reduction in its ability to bind to negatively charged lipid bilayers. The identification of myelin basic protein (phosphorylation at -pro-arg-thr-pro-) as a substrate for the erk kinases (fig. 1) demonstrates that there are other determinants important for substrate recognition than those present in the originally identified consensus sequence.

Phosphorylation decreased the ability of mbp to polymerize actin and to bundle actin filaments but had no effect on the dissociation constant of the mbp-actin complex or on the ability of ca2+-calmodulin to dissociate the complex. The most significant effect of phosphorylation on the mbp-actin complex was a dramatic reduction in its ability to bind to negatively charged lipid bilayers. The identification of myelin basic protein (phosphorylation at -pro-arg-thr-pro-) as a substrate for the erk kinases (fig. 1) demonstrates that there are other determinants important for substrate recognition than those present in the originally identified consensus sequence.

Our results suggest that map kinase can phosphorylate thr276 of smad4 and that phosphorylation can lead to enhanced tgf-beta-induced nuclear accumulation and, as a consequence, enhanced transcriptional activity of smad4.

Notch-induced degradation requires phosphorylation of E47 by p42/p44 MAP kinases. |Wild_type E47 but not the Mm mutant reacted to the antibodies, suggesting that E47 is at least phosphorylated at the M2 site (Figure 3A)|anti_phospho_M2 peptide (SSPSpTPVGSPQG)

Specifically, the complex formation between PTP-SL and ERK2 involves an unusual interaction leading to the phosphorylation of PTP-SL by ERK2 at Thr253 and the inactivating dephosphorylation of ERK2 by PTP-SL.

Erk, which is activated by hbx, associates with gsk-3beta through a docking motif ((291)fkfp) of gsk-3beta and phosphorylates gsk-3beta at the (43)thr residue, which primes gsk-3beta for its subsequent phosphorylation at ser9 by p90rsk, resulting in inactivation of gsk-3beta and upregulation of beta-catenin.

Transcriptional activation of p21(waf1/cip1) by alkylphospholipids: role of the mitogen-activated protein kinase pathway in the transactivation of the human p21(waf1/cip1) promoter by Sp1.|this activation promotes the phosphorylation of Sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased Sp1 binding and enhanced p21(waf1/cip1) transcription.

Transcriptional activation of p21(waf1/cip1) by alkylphospholipids: role of the mitogen-activated protein kinase pathway in the transactivation of the human p21(waf1/cip1) promoter by Sp1.|this activation promotes the phosphorylation of Sp1 in known mitogen-activated protein kinase residues (threonine 453 and 739), thereby leading to increased Sp1 binding and enhanced p21(waf1/cip1) transcription.

Cad is a multifunctional protein that initiates and regulates mammalian de novo pyrimidine biosynthesis. The activation of the pathway required for cell proliferation is a consequence of the phosphorylation of cad thr-456 by mitogen-activated protein (map) kinase.Activated map kinase (erk1/2), the enzyme responsible for the phosphorylation of thr-456, was also present in larger amounts in the nucleus than the cytosol

Using a number of different approaches it was demonstrated that the protein kinase acting on betaThr-613 and gammaThr-623 is the extracellular regulated kinase (ERK). It is suggested that an ERK-mediated phosphorylation of betaThr-613 and gammaThr-623 down-regulates the channel by facilitating its interaction with Nedd4.

Using a number of different approaches it was demonstrated that the protein kinase acting on betaThr-613 and gammaThr-623 is the extracellular regulated kinase (ERK). It is suggested that an ERK-mediated phosphorylation of betaThr-613 and gammaThr-623 down-regulates the channel by facilitating its interaction with Nedd4.

Phosphorylation of thr-69 by mapk14 and mapk11, and at thr-71 by mapk1/erk2, mapk3/erk1, mapk11, mapk12 and mapk14 in response to external stimulus like insulin causes increased transcriptional activity.

Phosphorylation of thr-69 by mapk14 and mapk11, and at thr-71 by mapk1/erk2, mapk3/erk1, mapk11, mapk12 and mapk14 in response to external stimulus like insulin causes increased transcriptional activity.

It is likely that the map2 and ert kinases account for the phosphorylation of the egf receptor at thr669 (egf receptor (krel veplt669psgeapnqallr)) observed in cultured cells.Phosphorylation at ser-695 is partial and occurs only if thr-693 is phosphorylated. Phosphorylation at thr-678 and thr-693 by prkd1 inhibits egf-induced mapk8/jnk1 activation.

Extracellular signal-regulated kinase phosphorylates tumor necrosis factor alpha-converting enzyme at threonine 735: a potential role in regulated sheddingwe show that extracellular signal-regulated kinase (erk) acts as an intermediate in protein kinase c-regulated trka cleavage. We report that the cytosolic tail of the tumor necrosis factor alpha-converting enzyme (tace) is phosphorylated by erk at threonine 735. In addition, we show that erk and tace associate. This association is favored by erk activation and by the presence of threonine 735. In contrast to the erk route, the p38 mapk was able to stimulate trka cleavage in cells devoid of tace activity, indicating that other proteases are also involved in trka shedding.

Erk-induced phosphorylation of b-raf on t753 promoted the disassembly of raf heterodimers, and the mutation of t753 prolonged growth factor-induced heterodimerization. The b-raf t753a mutant enhanced differentiation of pc12 cells, which was previously shown to be dependent on sustained erk signaling. Site is critical for v-src dependent modulation of slk kinase activity.

Erk-induced phosphorylation of b-raf on t753 promoted the disassembly of raf heterodimers, and the mutation of t753 prolonged growth factor-induced heterodimerization. The b-raf t753a mutant enhanced differentiation of pc12 cells, which was previously shown to be dependent on sustained erk signaling. Site is critical for v-src dependent modulation of slk kinase activity.

Here we report that ews and ews-fli1 become phosphorylated at thr79 in the n-terminal domain in response to mitogens or dna damage. Mitogen-induced phosphorylation of ews and ews-fli1 was weak and catalysed by erk1 (extracellular signal-regulated kinase 1) and erk2.

We show that phosphorylation of Smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (ERK1) increases the amount of Smad2 protein and leads to enhanced transcriptional activity.[] A site of ERK-dependent phosphorylation on Smad2 was located to Thr8

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

These results suggest that oncogenic ras, acting through mek1 and erk kinases, induces the phosphorylation of smad2 and smad3 .we show that phosphorylation of smad2, a mediator of the activin/transforming growth factor-beta signal, by activated extracellular signal-regulated kinase 1 (erk1) increases the amount of smad2 protein and leads to enhanced transcriptional activity

The activation of the mapk activity requires the dual phosphorylation of the ser/thr and tyr residues in the txy kinase activation motif (1113), and deactivation occurs through the action of either ser/thr protein phosphatase (14), protein-tyrosine phosphatase (ptp) (14, 15), or dual specificity phosphatases

Extracellular regulated kinases (ERK) 1 and ERK2 are authentic substrates for the dual-specificity protein-tyrosine phosphatase VHR. A novel role in down-regulating the ERK pathway.|Catalysis by VHR requires the native structure of ERK and is specific for tyrosine 185 of ERK2

When cells are stimulated with various ligands such as growth factors, hormones, neurotransmitters, or tumor promoters, erk1/2 is activated through dualphosphorylation at the -ptepy-motif. Subsequently, p-erk1/2 translocates into the nucleus and phosphorylates elk-1, thereby acting as a transcription factor for cell proliferationthese data indicate that sa-p-erk1/2 might not only be regulated by mkp such as rvhr, but also by pp1 and ptp as well

Here we demonstrate that inactivation of both erk1/2 and p38_ by dusp9/mkp-4 is mediated by a conserved arginine-rich kinase interaction motif located within the amino-terminal non-catalytic domain of the protein.

Here, we report that pea-15, a protein variably expressed in multiple cell types, blocks erk-dependent transcription and proliferation by binding erks and preventing their localization in the nucleus._ Pea-15 can redirect the biological outcome of map kinase signaling by regulating the subcellular localization of erk map kinase.

P-erk1/2 proteins were efficiently dephosphorylated in vitro by protein phosphatases 1 and 2a (pp1/2a) and mapk phosphatase 3 (mkp3). the dual specificity phosphatases that specifically dephosphorylate and inactivate the p-erk1/2 are called mapk phosphatases

A dominant-negative mutant of high cell densityenhanced ptp 1 (dep-1)//cd148 as well as reduction of its expression by rna interference partially restore vegfr-2 phosphorylation and map kinase activation.

We show that several proline-directed mitogen-activated protein kinases (mapks), such as p38, erk1/2, and jnk1 are sufficient and required for the phosphorylation of ppps/tp motifs of lrp6. External stimuli, which control the activity of mapks, such as phorbol esters and fibroblast growth factor 2 (fgf2) control the choice of the lrp6-ppps/tp kinase and regulate the amplitude of lrp6 phosphorylation and wnt/beta-catenin-dependent transcription.

A protein called mp1 (mek partner 1) was identified that bound specifically to mek1 and erk1 and facilitated their activation. When overexpressed in cultured cells, mp1 enhanced activation of erk1 and activation of a reporter driven by the transcription factor elk-1.

Ras signaling was shown previously to induce the phosphorylation of the bmp mediator smad1 at four erk consensus sites in the linker domain (kretzschmar et al. 1997a). Phosphorylation of these four sites inhibits smad1 accumulation in the nucleus

Spin90 was phosphorylated by erk1, which was, itself, activated by cell adhesion and platelet-derived growth factor. Such phosphorylation of spin90 likely promotes the interaction of the spin90.betapix.wasp complex and nck

The phosphorylation of raptor is stimulated by insulin and inhibited by rapamycin. Importantly, the site-directed mutation of raptor at one phosphorylation site, Ser(863), reduced mTORC1 activity both in vitro and in vivo.

We found three proline-directed residues within raptor, ser(8), ser(696), and ser(863), which are directly phosphorylated by erk1/2. Expression of phosphorylation-deficient alleles of raptor revealed that phosphorylation of these sites by erk1/2 normally promotes mtorc1 activity and signaling to downstream substrates, such as 4e-bp1.